Axle driving unit for a lawn tractor

Abstract

An axle driving unit having a housing ( 21,22 ) for supporting a first axle ( 17 ) for mounting thereon a first driving wheel ( 3 L), and a longer second axle ( 18 ) for mounting thereon a second driving wheel ( 3 R). The axle driving unit is eccentrically mounted on a body frame ( 1 ) in proximity to the first driving wheel ( 3 L). A speed change transmission (T) is disposed in an enlarged region of the housing that extends substantially perpendicularly with respect to the axles ( 17,18 ). The axle driving unit can thus be easily disposed to the side of a chute ( 6 ) of a rear-discharge type lawn tractor.

What is claimed is:  
     
       1. An axle driving unit, comprising: 
       a pair of axles;  
       a differential unit differentially connecting said pair of axles to each other;  
       a hydraulic pump;  
       a hydraulic motor having a motor shaft whose torque is transmitted to said differential unit;  
       a center section onto which said hydraulic pump and said hydraulic motor are mounted so as to be fluidly connected with each other through said center section;  
       a housing containing said pair of axles, said differential unit, said hydraulic pump, said hydraulic motor and said center section; and  
       a bolt fastening said center section to said housing, wherein longitudinal directions of said bolt and said motor shaft are parallel to each other.  
     
     
       2. The axle driving unit as set forth in  claim 1 , wherein said hydraulic pump has a pump shaft whose longitudinal direction is parallel to the longitudinal direction of said motor shaft. 
     
     
       3. The axle driving unit as set forth in  claim 1 , wherein the longitudinal direction of said motor shaft is perpendicular to a longitudinal direction of said pair of axles. 
     
     
       4. The axle driving unit as set forth in  claim 1 , said differential unit further comprising: 
       an input gear to receive the torque of said motor shaft;  
       a planetary gear for transmitting the rotation of said input gear to said pair of axles; and  
       a pivot pin for pivoting said planetary gear, wherein said pivot pin is directly supported by said input gear.  
     
     
       5. An axle driving unit, comprising: 
       a pair of axles;  
       a differential unit differentially connecting said pair of axles to each other;  
       a hydraulic pump;  
       a hydraulic motor having a motor shaft whose torque is transmitted to said differential unit;  
       a center section onto which said hydraulic pump and said hydraulic motor are mounted so as to be fluidly connected with each other through said center section;  
       a housing containing said pair of axles, said differential unit, said hydraulic pump, said hydraulic motor and said center section, said housing being constituted by a first housing part and a second housing part joined to each other, wherein said hydraulic pump and said hydraulic motor are entirely disposed in said first housing part; and  
       a bolt fastening said center section to said first housing part, wherein longitudinal directions of said bolt and said motor shaft are parallel to each other.  
     
     
       6. The axle driving unit as set forth in  claim 5 , wherein said hydraulic pump has a pump shaft whose longitudinal direction is parallel to the longitudinal direction of said motor shaft. 
     
     
       7. The axle driving unit as set forth in  claim 6 , wherein the longitudinal direction of said motor shaft is perpendicular to a longitudinal direction of said pair of axles. 
     
     
       8. The axle driving unit as set forth in  claim 6 , said differential unit further comprising: 
       an input gear to receive the torque of said motor shaft;  
       a planetary gear for transmitting the rotation of said input gear to said pair of axles; and  
       a pivot pin for pivoting said planetary gear, wherein said pivot pin is directly supported by said input gear.  
     
     
       9. An axle driving unit, comprising: 
       a pair of axles;  
       a differential unit differently connecting said pair of axles to each other;  
       a hydraulic pump;  
       a hydraulic motor having a motor shaft whose torque is transmitted to said differential unit;  
       a center section having a pump mounting surface and a motor mounting surface onto which said hydraulic pump and said hydraulic motor are mounted respectively so as to be fluidly connected with each other through said center section;  
       a housing containing said pair of axles, said differential unit, said hydraulic pump, said hydraulic motor and said section, said housing being constituted by a first housing part and a second housing part joined to each other at a joint surface, wherein said hydraulic pump and said hydraulic motor are entirely disposed in said first housing part, and wherein said motor mounting surface is disposed in parallel to said joint surface of said housing; and  
       a bolt fastening said center section to said first housing part.  
     
     
       10. The axle driving unit as set forth in  claim 9 , wherein longitudinal directions of said motor shaft and said bolt are parallel to each other. 
     
     
       11. The axle driving unit as a set forth in  claim 9 , wherein said hydraulic pump has a pump shaft whose longitudinal direction is parallel to a longitudinal direction of said motor shaft. 
     
     
       12. The axle driving unit as set forth in  claim 9 , wherein a longitudinal direction of said motor shaft is perpendicular to a longitudinal direction of said pair of axles. 
     
     
       13. The axle driving unit as set forth in  claim 9 , said differential unit further comprising: 
       an input gear to receive the torque of said motor shaft;  
       a planetary gear for transmitting the rotation of said input gear to said pair of axles; and  
       a pivot pin for pivoting said planetary gear, wherein said pivot pin is directly supported by said input gear.  
     
     
       14. An axle driving unit, comprising: 
       a pair of axles;  
       a differential unit differentially connecting said pair of axles to each other;  
       a hydraulic pump;  
       a hydraulic motor having a motor shaft whose torque is transmitted to said differential unit;  
       a center section having a pump mounting surface and a motor mounting surface onto which said hydraulic pump and said hydraulic motor are mounted respectively so as to be fluidly connected with each other through said center section, wherein said motor shaft projects outward from said center section;  
       an output gear provided on a projecting portion of said motor shaft outside said center section;  
       a housing containing said pair of axles, said differential unit, said hydraulic pump, said hydraulic motor and said center section, said housing being constituted by a first housing part and a second housing part joined to each other at a joint surface, wherein said hydraulic pump and said hydraulic motor are entirely disposed in said first housing part, wherein said center section is detachably attached to said housing, and wherein said motor mounting surface is disposed in parallel to said joint surface of said housing; and  
       a gear train interposed between said output gear and said differential unit, wherein said gear train is arranged between said center section and said second housing part.  
     
     
       15. The axle driving unit as set forth in  claim 14  further comprising: 
       a bolt fastening said center section to said first housing part, wherein longitudinal directions of said motor shaft and said bolt are parallel to each other.  
     
     
       16. The axle driving unit as set forth in  claim 14 , wherein said hydraulic pump has a pump shaft whose longitudinal direction is parallel to a longitudinal direction of said motor shaft. 
     
     
       17. The axle driving unit as set forth in  claim 14 , wherein a longitudinal direction of said motor shaft is perpendicular to a longitudinal direction of said pair of axles. 
     
     
       18. The axle driving unit as set forth in  claim 14 , said differential unit further comprising: 
       an input gear to receive the torque of said motor shaft;  
       a planetary gear for transmitting the rotation of said input gear to said pair of axles; and  
       a pivot pin for pivoting said planetary gear, wherein said pivot pin is directly supported by said input gear.